The rubber bands that adjust the brush length allow for many sounds. I use one adjusted to the "solid" setting- to get a nice heavy beat, and the other one loose. I also use one of these at solid setting with another more conventional nylon brush for even more variety. I can see the little rubber bands that adjust length breaking at some point, but probably could use any small rubber band to achieve the same thing.

Nice alternative to metal brushes, different sound.These have a nice weight, and give a nice mellow brush sound on the cajon.Seems to be fairly well made. Don't know yet how it will hold up to heavy use.A little pricey for what they are.